...the "mind-body problem" is essentially an artifact of the early modern philosophers' decision to abandon a hylemorphic conception of the world for a mechanistic one, and its notorious intractability is, in the view of Thomists, one of the starkest indications of how deeply mistaken that decision was.Feser makes an excellent point.
Consider: if modern philosophy finds the mind itself-- the most basic apparatus with which we perceive reality-- a Gordian Knot, perhaps the problem is not with the intractability of the mind itself, but with the inadequacy of the philosophical systems we are using to try to explain it.
Beginning with Descartes in the early modern period philosophers adopted a mechanical view of nature, in contrast with the hylemorphic understanding of nature that had dominated philosophy since Aristotle.
Hylemorphism (hyle- matter, morph- form) is the view that nature is best understood as substance comprised of prime matter and form. Form is what makes a thing intelligible. Matter is what makes it individual.
Change in nature was understood as comprising four causes:
1) Material cause- what something is made of
2) Formal cause- the intelligible principle that makes something what it is
3) Efficient cause- the agent that brings the change about
4) Final cause- the directionality of the change-- the 'to' in 'from--- to'
In the hylemorphic understanding of nature, 'pointedness', which is the idea that something 'refers to' something else, is intrinsic to nature.
The hylemorphic understanding of the mind is that the soul is the form of the body, akin to the form of a rock or the form of a chair. But a form of a living thing is a soul, which has powers. These powers include sensation, intellect, judgement, will, etc.
The mind is a form, but it has a property unlike the forms of objects: it can acquire the form of something else and remain itself. This is what 'thought' is.
When we think about something (say... about a tree in the front yard), the form of the tree is taken in our mind, while the matter (of course) is not. With the form of the tree (technically. the "intelligible principle" ) of the tree in our mind, we can contemplate the tree using our powers of intellect.
The hylemorphic understanding of nature seems alien to us, but it provides a clear and coherent explanation of the mind. As Feser points out, "the mind-body problem" wasn't a problem until early modern philosophers made it a problem.
Philosophy is supposed to solve problems. Modern philosophy too often creates problems.
The modern error was to abandon hylemorphism and to adopt a 'mechanical philosophy'. Mechanical philosophy is the abandonment of formal and final cause-- the abandonment of essences and teleology in nature. Only retained were truncated efficient and material causes.
The problem vis-a-vis the mind is that if one eliminates essences and teleology from nature, then qualia (the subjective experience of sensations) and intentionality (the 'aboutness' of a thought) become inexplicable. If nature is mere matter in motion, the mind must remain unexplained, because matter in motion intrinsically can't explain subjectivity or reference to things in the world.
As Feser has observed, modern philosophers, having abandoned teleology, have explained the apparent directedness of natural processes as a trick of our minds. They've swept teleology under the mental rug. Now, when confronted with the obvious directedness of the mind itself, modern philosophers have no rug left to sweep things under.
There is really no "mind-body problem". There's a 'bad philosophy problem', self-inflicted.
Why have philosophers embraced bad philosophy and cast aside good philosophy? Some of the reason is laziness (scholastic philosophy is hard), and some is ignorance (some very accomplished modern philosophers don't have much genuine knowledge of scholasticism).
But I suspect that there's a deeper reason. All scholastics have been theists. The hylemorphic understanding of nature naturally leads to theism, even to the Christian understanding of God. Aquinas's Five Ways and the Ontological Argument depend critically on a hylemorphic understanding of reality.
Modern philosophy on the mind-body 'problem' is a paradigm of willful ignorance. Many philosophers would rather embrace bad philosophy than venture into a system that points to God.
* from Aquinas p132